This invention relates to devices for dispensing foams formed by admixing compatible and biologically acceptable gases and foamable liquids. More particularly, the invention relates to foam producing devices for use with fluids which tend to clog the pores of conventional foam dispensing devices said devices also permitting the dispensing, if desired, of the fluid as a liquid rather than a foam.
Numerous foam dispensing devices of a non-aerosol type, which are essentially hand held squeeze bottles of relatively small capacity, have been described in, e.g., U.S. Pat. Nos. 3,709,437 and 3,937,364. However, their characteristics cannot be extrapolated to devices of economically desirable large capacity. This is due to the fact that pressure and liquid capacity control is difficult to achieve in view of the small size required in the foam producing means to produce the most desired foams.
U.S. Pat. No. 4,531,660 describes a device intended to overcome the above disadvantages by placing a small inner chamber, associated with the foam producing means, said combination maximizing the foam quality, within a large chamber or reservoir of economically desirable large capacity.
However, said devices suffer from the disadvantage that, after mixing of the gases and liquids, the foams must be passed through porous materials before being dispensed. As a result, in the case of certain fluids, such as Povidone.TM., the pores of the foam producing means are ultimately clogged. This is a consequence of the foams having to pass through the pores of the foam producing means.
It is believed, although the theory is not essential to the practice of the invention, that fluids, such as Povidone.TM., which are based on polymeric materials, clog the pores of the the porous elements of the foam producing devices by separation and buildup of the polymeric moieties upstream of and/or within the pores of the porous elements.
Furthermore, the described inventions make no provision for dispensing the foamable liquid in a liquid form, if desired, as an alternative to the foam form.
In my U.S. Pat. No. 4,901,925, incorporated herein by reference, there is described a foam dispensing device comprising a foam producing device which obviates the above problem in that the mixing of the components of the foam occurs only after diffusion of the gas through the pores of the porous elements. Thus the foam never passes through any pores and clogging thereof is prevented. Foaming occurs only in the portion of a mixing chamber which is open to the atmosphere and the foam does not have to pass any obstructions before being dispensed to the user.
It has now been found, in accordance with the instant invention that a more simple foam dispensing device may be prepared if dispensing of the foamable liquid, itself, is not required.
It is to be understood throughout the application that references to air and gas may be used interchangably and that the term gas refers to compatible and biologically acceptable gases such as nitrogen.